The controversial condition is increasingly blamed when someone dies in police custody or in other stressful situations. Rights groups call it a scapegoat.

On a sweltering afternoon last June, police in Salinas responded to a 911 call about a suspicious man running aimlessly through downtown traffic, acting erratically and complaining of chest pain. The officers tried several times to calm the man, a 41-year-old local resident named Gregory Patton. When that didn't work, they caught him, forced him to the ground and tried to bind his hands and feet together, a law enforcement restraint technique known as hogtying.

According to the police report, Patton struggled for several minutes -- and continued to complain of chest pain. The police called for paramedics, but before they arrived Patton stopped breathing. He was pronounced dead not long after arriving at a hospital.

Patton's family and civil rights groups immediately questioned whether excessive police force contributed to Patton's death. But according to the medical examiner, the cause was a controversial and largely unknown medical condition called excited delirium.

Although it's considered rare, medical examiners around the country are now using excited delirium to explain a significant number of in-custody deaths. Indeed, although no one tracks the number of suspected cases -- nor are there any public records on the number of people who die in police custody -- researchers suspect that the condition accounts for a half-dozen deaths in most major cities each year. By some estimates, excited delirium is now being ruled as the reason behind the majority off all in-custody deaths.

The Patton case was the second time in nine months that an in-custody death in Salinas -- a city of 150,000 people -- was attributed to the condition.

"This is happening every day," says Dr. Steven Karch, a cardiac pathologist and assistant medical examiner in San Francisco. "Every time you hear of a man acting crazy and running naked in the middle of the street or someone on drugs comes into the emergency room with six police officers on their arms, it's excited delirium."

It's a trend that worries police watchdogs and civil rights groups such as the National Assn. for the Advancement of Colored People and the American Civil Liberties Union. They fear that the condition is being exploited and used as a medical scapegoat for police abuse. Some point out that most medical associations don't recognize it. "We've never heard of it," says a spokesman for the American Medical Assn.

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A defense in civil lawsuits

Already, the syndrome is being used as a defense in several civil lawsuits against police filed by families of those who've died in custody. That includes two civil cases in the last three years against the Los Angeles County Sheriff's Department over the deaths of suspects who had been restrained by officers. The outcomes were mixed.

"This is a smokescreen. I've never seen any proof that someone can be excited to death, and that's essentially what they are saying," says Van Jones, executive director of the San Francisco-based Ella Baker Center for Human Rights.

According to neurologists and medical examiners who have researched the issue, excited delirium is an often-fatal condition that can occur in a small subset of people who use drugs, mostly stimulants like cocaine or methamphetamines, over a long period of time. Typically, as users continue to take the drugs, the number of drug receptors in the brain rises, which helps pump dopamine and other excess hormones out of the brain.

But in people at risk of excited delirium, there is a genetic fault that impairs the brain's ability to increase those receptors, they say. After drug use, that can lead to a dangerously high level of hormones in a part of the brain known as the amygdala, which later can bring on delirium, paranoia and aggression. More often than not, that attracts the police.

In such instances, even a minimal struggle can lead to too much pressure on the heart or lungs and the person can die. Another problem: Long-term stimulant use can enlarge and weaken the heart, which can be overtaxed during a big adrenaline rush. "It's a very dangerous toxic mix of events," says Karch.

The condition is starting also to be diagnosed outside of law enforcement. Two years ago, the death of a 16-year-old mentally disabled girl who died while being restrained at school was attributed to the condition, according to the medical report, as have been a number of cases involving suspected shoplifters and store security guards. It was also blamed for the death of Darrell Porter last summer, the MVP of the 1982 World Series, who died after a car accident and was later found to have cocaine in his system. Still, there are almost no studies on cases outside of law enforcement. So for now, the focus remains on the police.

Researchers and doctors who recognize the condition say it isn't unusual that most major medical associations such as the AMA don't; they wouldn't come across it, they say. The National Assn. of Medical Examiners has recognized it for more than a decade.